Added calculateWitness method (#9)

* added calculateWitness method

* fix

* types

* fix

* typo

* added test & typo

* typo

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@solarity/zkit",
-  "version": "0.2.3",
+  "version": "0.2.4",
   "license": "MIT",
   "author": "Distributed Lab",
   "readme": "README.md",

src/core/CircuitZKit.ts

@@ -1,13 +1,14 @@
 import ejs from "ejs";
 import fs from "fs";
+import * as os from "os";
 import path from "path";
 import * as snarkjs from "snarkjs";
 
 import {
   ArtifactsFileType,
   Calldata,
   CircuitZKitConfig,
-  Inputs,
+  Signals,
   ProofStruct,
   VerifierTemplateType,
 } from "../types/circuit-zkit";
@@ -54,16 +55,37 @@ export class CircuitZKit {
     fs.writeFileSync(verifierFilePath, verifierCode, "utf-8");
   }
 
+  /**
+   * Calculates a witness for the given inputs.
+   *
+   * @param {Signals} inputs - The inputs for the circuit.
+   * @returns {Promise<bigint[]>} The generated witness.
+   */
+  public async calculateWitness(inputs: Signals): Promise<bigint[]> {
+    const tmpDir = path.join(os.tmpdir(), ".zkit");
+
+    if (!fs.existsSync(tmpDir)) {
+      fs.mkdirSync(tmpDir, { recursive: true });
+    }
+
+    const wtnsFile = path.join(tmpDir, `${this.getCircuitName()}.wtns`);
+    const wasmFile = this.mustGetArtifactsFilePath("wasm");
+
+    await snarkjs.wtns.calculate(inputs, wasmFile, wtnsFile);
+
+    return (await snarkjs.wtns.exportJson(wtnsFile)) as bigint[];
+  }
+
   /**
    * Generates a proof for the given inputs.
    *
    * @dev The `inputs` should be in the same order as the circuit expects them.
    *
-   * @param {Inputs} inputs - The inputs for the circuit.
+   * @param {Signals} inputs - The inputs for the circuit.
    * @returns {Promise<ProofStruct>} The generated proof.
    * @todo Add support for other proving systems.
    */
-  public async generateProof(inputs: Inputs): Promise<ProofStruct> {
+  public async generateProof(inputs: Signals): Promise<ProofStruct> {
     const zKeyFile = this.mustGetArtifactsFilePath("zkey");
     const wasmFile = this.mustGetArtifactsFilePath("wasm");
 

src/types/circuit-zkit.ts

@@ -22,11 +22,10 @@ export type ProofStruct = {
   publicSignals: PublicSignals;
 };
 
-export type NumberLike = number | bigint | string;
+export type NumberLike = number | bigint | `${number}`;
 export type ArrayLike = NumberLike[] | ArrayLike[];
-export type InputLike = NumberLike | ArrayLike;
-
-export type Inputs = Record<string, InputLike>;
+export type Signal = NumberLike | ArrayLike;
+export type Signals = Record<string, Signal>;
 
 export type ArtifactsFileType = "r1cs" | "zkey" | "vkey" | "sym" | "json" | "wasm";
 export type VerifierTemplateType = "groth16";

test/CircuitZKit.test.ts

@@ -1,6 +1,7 @@
 import ejs from "ejs";
-import path from "path";
 import fs from "fs";
+import * as os from "os";
+import path from "path";
 
 import { expect } from "chai";
 import { useFixtureProject } from "./helpers";
@@ -177,6 +178,32 @@ describe("CircuitZKit", () => {
     });
   });
 
+  describe("calculateWitness", () => {
+    useFixtureProject("simple-circuits");
+
+    it("should correctly create witness", async () => {
+      const circuitName = "Multiplier";
+      const circuitArtifactsPath = getArtifactsFullPath(`${circuitName}.circom`);
+
+      const multiplierCircuit: CircuitZKit = new CircuitZKit({
+        circuitName,
+        circuitArtifactsPath,
+        verifierDirPath: getVerifiersDirFullPath(),
+      });
+
+      const b = 10,
+        a = 20;
+
+      const tmpDir = path.join(os.tmpdir(), ".zkit");
+
+      fs.rmSync(tmpDir, { force: true, recursive: true });
+
+      expect(await multiplierCircuit.calculateWitness({ a, b })).to.deep.eq([1n, 200n, 20n, 10n]);
+      expect(await multiplierCircuit.calculateWitness({ a, b })).to.deep.eq([1n, 200n, 20n, 10n]);
+      expect(await multiplierCircuit.calculateWitness({ a, b: 30 })).to.deep.eq([1n, 600n, 20n, 30n]);
+    });
+  });
+
   describe("generateProof/verifyProof", () => {
     useFixtureProject("simple-circuits");